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OTHER WORLDS THAN THIS 




UNIFORM WITH THIS VOLUME 


HOW THE WORLD BEGAN 

The Story of the Beginning of Life on Earth 

HOW THE WORLD GREW UP 

The Story of Man 

HOW THE WORLD IS RULED 

The Story of Government 

THE WORLD OF ANIMALS 

The Story of Animals 

THE GARDEN OF THE WORLD 

The Story of Botany 

HOW THE WORLD IS CHANGING 

The Story of Geology 

THE WORLD’S MOODS 

The Story of the Weather 

THIS PHYSICAL WORLD 

The Story of Physics 

WHAT MAKES UP THE WORLD 

The Story of Chemistry 


Thomas S. Rockwell Company 
Publishers 
CHICAGO 








Publishers Note 


This book presents in popular form the 
present state of science. It has been reviewed 
by a specialist in this field of knowledge. An 
excerpt from his review follows: 

“This good effort to bring to 
younger minds some of the simple 
facts and laws of astronomy meets 
with my whole-hearted approval 


Signed: 

William Duncan MacMillan 
Professor of Astronomy 
The University of Chicago 







On the moon the earth would shine with a light forty 
times greater than moonlight 
















OTHER WORLDS THAN THIS 


By 

Elena Fontany 

n 

Drawings by 
John Dukes McKee 



THOMAS S. ROCKWELL COMPANY 

CHICAGO 

1930 



Copyright, 1930, by 
THOMAS S. ROCKWELL COMPANY 
CHICAGO 


Printed in United States of America 

©CIA 30501 

NOV 10 1930 




CONTENTS 




What is the sun made of? How do we know the 
sun is made of gas? Is the sun the same on the 
inside as on the outside? Is the sun made of the 
same stuff as the earth? How hot is the sun? 

What makes the sun so hot? Why doesn’t the sun 
cool off? What is an eclipse of the sun? Where 
can a total eclipse be seen? What does an eclipse 
of the sun look like? What do the astronomers do 
during an eclipse? Why are astronomers inter¬ 
ested in eclipses of the sun? 

IV A Trip to the Moon 43 

How far away is the moon? What does the earth 
look like from space? What is a globe of the 
moon like? What is space like? What is the sur¬ 
face of the moon like? What is the climate of the 
moon? What does the sky look like from the 
moon? How far could we see on the moon? Is 
there moon magic? What is a night on the moon 
like? Why does the moon change from crescent to 
full moon? What are the scenic wonders of the 
moon? Are there people in the moon? What 
about the hare in the moon? What about the man 
in the moon? What about the lady in the moon? 


I How the Earth Began ii 

What was the sun like before the earth was born? 

How did Newton discover gravitation? What is 
the law of gravitation? How does the force of 
gravity work? What was the sun made of? 

What happened when our sun met the magnificent 
visitor? What happened to the sun’s lost par¬ 
ticles? What is a spiral? 

II A Bird’s-Eye View of the Solar System 21 

Are planets like stars? Why are planets as bright 
as the brightest stars? How many planets are 
there? How big are the planets? 

Ill Secrets of the Sun 20 


V Our Nearest Neighbors 


6i 


Which planet is smallest? How does Mercury look 
from the earth? Why is a day a whole year long? 
Is Mercury a two-faced world? What is the cli¬ 
mate of Mercury? Why is Mercury twice as hot 
in summer? Which is the evening star? Why is 
Venus the earth's twin? Is Venus inhabited? 
What is the Venusian climate? What would the 
earth look like from Venus? What do other 
planets look like from Venus? Could men live on 
any other planet? How does Mars differ from the 
earth? What is the climate of Mars? What are 
the moons of Mars like? What are Mars' polar 
caps made of? What are the canals of Mars? Is 
Mars a dying world? 


84 


VI Our Big Brothers 


Which is the largest planet? What are the nine 
moons of Jupiter? Why does Jupiter have a 
month half a day long? Is Jupiter inhabited? 
What have Venus and Jupiter in common? Is 
Jupiter a world of ice? What does Jupiter look 
like from the earth? Who discovered Saturn's 
rings? What do Saturn's rings look like? What 
are the rings made of? How do we know that 
SaUirn is the' youngest planet? Why is there gas 
in the rings? When was Uranus found to be a 
planet? Why does Uranus shine so faintly? Why 
has Uranus such a long year and such a short day? 
Are there- people on Uranus? Can Neptune be 
seen? What do we know about Neptune? Why 
does the sun rise in the west and set in the east? 
Do people live on Neptune? Is there another 
planet? How was it discovered? What is it like? 
Why do we not know more about it? Are there 
other planets? 


VII And Then What? 


107 


What will become of the earth? What will become 
of the sun? What would become of the solar 
system? Will new worlds be created? 


LIST OF ILLUSTRATIONS 


On the moon the earth would shine with a light forty 
times greater than moonlight (frontispiece) 

This every-day happening is said to have given Newton 
the answer 15 

The man with the greatest pulling power is not always 
the biggest nor always the nearest 17 

If you are only a yard from the tree it ta\es less time to 
run around it 25 

This map gives an idea of the distances of the various 
planets from the sun 27 

The outermost layer of the sun loo\s like a silver halo 
and is called the corona 32 

At this moment in the eclipse the leaping flames of the 
suns color-sphere are faintly visible 39 

Our moon turns only one side of its face toward the earth 
—the other is invisible 47 

Many of the cup-like craters of the moon have walls that 
rise two miles high 51 

If Mars is inhabited, the people can comfortably support 
bodies fourteen feet tall 71 

Through a telescope Mars becomes a beautiful disk* 
greenish blue lines across it 77 

Jupiter as it would appear if it were the same distance 
from the earth as the moon 88 

Any one of the great outer planets is larger than the en¬ 
tire group of terrestrial planets 93 

Eventually the world will die out and become a dry 
barren thing with no life upon it 111 





Chapter I 


HOW THE EARTH BEGAN 

T HERE was once a time when our earth 
did not exist. It was a very long time ago, 
thousands of millions of years ago, perhaps ten 
thousands of millions. No one knows exactly 
how long. The earth, the moon, Mars, Venus 
and all the other planets were a part of the Sun. 
And the Sun was traveling through space— 
alone. 

Strange as it may seem, the Sun looked 
almost the same as it does now. It shone with 
the same fierce, white light. And it appeared 
to be exactly the same size. Even with all the 
planets a part of it, it could scarcely have been 
one-thousandth part bigger than it is today. If 
you yourself suddenly became one-thousandth 
part bigger, no one would be able to tell the 
difference. 


What was the 
sun li\e before 
the earth was 
born? 


11 


12 


OTHER WORLDS THAN THIS 


As a childless star our Sun was one of a 
million lonely wanderers through the heavens. 
All around it was an empty space trillions of 
miles wide. The nearest neighbors were so 
far away they looked like pinpricks in the sky. 
Robinson Crusoe was never more alone than 
our sun on his desert island of space. Other 
stars, like ships that passed Crusoe’s Island by, 
would come and go, but they never approached 
hailing distance. 

The chances of one star meeting another were 
very small. But one day a new star appeared 
in the heavens. It seemed to be aiming straight 
at the sun. For thousands of years it kept 
coming closer and closer. It swept through 
the vast stretches of ether at a tremendous pace. 

All this time our sun was traveling, too. 
The nearer the stars came to each other, the 
faster they moved. Horseshoe magnets come 
together with a click. But the power that drew 
the two suns together was not magnetism. It 
was gravity. Gravity is what makes the world 
go round. And it keeps the stars and planets 


HOW THE EARTH BEGAN 


J 3 


in their places. It has always existed and people 
have noticed it. Just as electricity has always 
existed and been noticed. But for centuries no 
one understood much about it. 

An English astronomer, Sir Isaac Newton, 
was the first to discover what gravity’s laws and 
principles were. 

When Isaac Newton was in his twenty-fourth 
year there was a terrible plague in England. 
All the schools and universities were shut down. 
During the long vacation that followed, he had 
time to think about many things. He wondered 
about the sun and the stars. And he wondered 
why the moon did not fly away from the earth, 
but kept going around and around it, like a 
weight on the end of a string that a boy twirls 
about his head. 

One afternoon, so the story goes, he lay half 
asleep in an orchard. An apple fell from the 
branch directly over him. This everyday hap¬ 
pening is said to have given Newton the answer 
to a question that had puzzled all the great 
astronomers before him. There and then he 


How did Newton 
discover 
gravitation? 


14 


OTHER WORLDS THAN THIS 


What is the 
law of 
gravitation? 


How does the 
force of 
gravity wor\? 


is supposed to have discovered the law of grav¬ 
itation. The story that astronomers tell us is a 
far different tale, a version not half so romantic 
or nearly so well known. It is, however, the 
true story of Newton’s long hours of careful 
mathematical calculations. 

The law of gravitation is very plain. It is 
surprising that no one had ever proved it before. 
Everything in the universe attracts everything 
else. That is, every particle or piece, or body 
of matter attracts every other particle of matter. 
The force of this attraction depends on the size 
of the objects attracting each other, as well as 
on their distance apart. 

Let us think of these objects or particles of 
matter as so many men of different sizes. Some 
are giants three miles high. Others are as tall 
as a skyscraper. Some are average size. Others 
are four foot pygmies. Some are the size of 
Tom Thumb. And still others are no bigger 
than a flea. Then, suppose that a large number 
of ropes connect each man with every other 
man. Suppose, too, that each man is having a 


HOW THE EARTH BEGAN 


15 


tug of war with every other. Which man will 
have the greatest pulling power? 

You know from experience how easy it is 
for a boy that is much bigger than you are to 



This every-day happening is said to have given 
Newton the answer 


pull you over. And it is still easier for him to 
pull you over if there is a short rope rather than 
a long rope between you. But lengthen the rope 
to a mile and he will not be able to move you 
one inch, no matter how hard he tugs. Now 
suppose your friend becomes a giant three miles 
high. He gives a jerk and there you go, flying 
toward him like a fish pulled in by a casting 
line or like an apple falling toward the earth. 





i6 OTHER WORLDS THAN THIS 

In order to make it quite impossible for him to 
move you, you must place him several thousands 
of miles away. It is easy to see from this that 
the man with the greatest pulling power is not 
always the biggest nor always the nearest, but 
the man who is near enough for his bigness to 
count. 

A boy your own size playing tug of war with 
a rope two yards long has more chance of mov¬ 
ing you than a giant thousands of miles away. 
This is why the moon does not fall toward the 
sun but falls around and around the earth. It 
is also the reason why the planets do not leave 
the solar system for a bigger star but are forever 
falling around their parent sun. If the moon 
were nearer or the earth bigger, the earth would 
swallow the moon. And if the sun were bigger 
and nearer it would swallow the earth. Every 
star, every planet, and every heavenly body is 
pulling on every other one. They manage to 
keep apart and do not fall together in a heap 
because of the influence of their neighbors as 
well as their own pulling power. 



The man with the greatest pulling power . is not al¬ 
ways the biggest nor always the nearest 


17 

















i8 


OTHER WORLDS THAN THIS 


What was the 
sun made of? 


What happened 
when our sun 
met the magnifi¬ 
cent visitor? 


Even in its childless days, our great white 
sun was gaseous. And so was its visitor. It 
was made up of tiny particles of matter, like 
a fog. If a stone could have been pitched 
through it without melting, it would have come 
out at the other side as easily as a bullet striking 
through a cloud. 

When the two stars were near enough to feel 
each other’s presence, the tiny particles of our 
sun were attracted by the newcomer. They 
swept toward it like a giant tide. As the two 
grew nearer, the tides became even bigger, and 
the bigger they grew, the more fiercely they 
whirled and spun. It seemed the suns had 
melted into one another. Actually they were 
still millions of miles away. A terrible battle 
followed. Each sun struggled to get free from 
the other. It was a real tug of war between 
enemies well matched in size and strength. 
But both were traveling at a terrific speed, and 
in opposite directions. Nothing could have 
stopped them except a head-on collision. They 
finally wrenched themselves apart. And each 


HOW THE EARTH BEGAN 


i9 


strove for all he was worth to hold on to the 
millions of tiny particles that had left him for 
the other. Some of these particles our sun was 
able to pull back. But some were too far 
away. He could never force them to return. 

Much as the children of Hamelin followed 
the Pied Piper the particles that left our sun 
followed the wonderful visitor. When he 
was alongside their home in the sun they shot 
straight out to meet him. But when he passed 
their home they had to cut corners so as to keep 
up. If you wanted to ride in an automobile 
that was coming down the street in front of 
your house, you would run directly out toward 
the roadway to meet it. But if the automobile 
passed you before you reached the street, you 
would cut across the yard to head if off. Now 
suppose someone ran behind you and put a peb¬ 
ble in every footprint. You would find you had 
run on a curve. 

This is just what the particles of the sun did, 
too. They ran on a curve. When the visiting 
star finally got so far away that the particles 


What happened 
to the suns 
lost particles? 


20 


OTHER WORLDS THAN THIS 


What is a spiral? 

\ 



could not follow him any more, they found 
themselves in curved lines shooting out from 
the sun and revolving around and around it. 

This revolving scattered material was like a 
mist of fire. But astronomers, being more in¬ 
terested in its peculiar shape, have called it a 
spiral. Spiral means a winding curve. Our 
sun’s spiral happened to contain some particles 
bigger than others. These bigger particles 
had more “pull” or gravity than the smaller 
ones. So they gradually swept up the re¬ 
maining and smaller particles just as a little 
snowball will pick up more snow and grow into 
a big snowball. Eventually the particles grew 
into planets of different sizes. They were not 
all the same size, because some were bigger to 
start with. And some of them traveled in parts 
of the sky where there were more particles to 
pick up. 

As you may have guessed, one of the planets 
was our own earth. And this is the story of 
how our Solar System was created. 


7, 


Chapter II 


A BIRD’S-EYE VIEW OF THE 
SOLAR SYSTEM 

T HE Roman god of the Sun was called Sol. 

From his name we get the word Solar. 
The Solar System means the system of the sun. 
It includes the sun, planets, and the satellites 
or moons, which move around the planets. 

To most of us the planets seem exactly like 
stars. But suppose we were shepherds or 
astronomers and could watch them night after 
night for several months. We would be sure 
to notice a difference between them. In the 
course of the year, the stars rise, move across the 
heavens and set, traveling from east to west as 
the sun does. They march in a fixed order, as 
though on parade. But the planets seem to have 
an odd way of moving in respect to the rest of 
the pageant. Each one of them appears to have 
a road of travel all his own. This is why the 


Are planets 
like stars? 


21 


22 


OTHER WORLDS THAN THIS 


Why are planets 
as bright as the 
brightest stars? 


shepherds of ancient Greece called them planets 
or wanderers. We know today that the planets 
do not really wander because they all journey 
around the sun. But they move very slowly. 
So it not only takes months to discover that 
they are actually out of step with the stars but 
it takes years to trace their orbits. 

Perhaps the quickest way of telling the dif¬ 
ference between stars and planets is to look at 
them through a telescope. Under a telescope 
the planets appear much larger. They look like 
tiny moons, round and disc-like. But the stars, 
as the great Galileo once said, “appear of the 
same shape as when they are viewed by simply 
looking at them.” They are merely bright 
points of light. 

Then again, the planets shine with a steady, 
calm light and seldom change in color, while 
the twinkling stars will change all colors of the 
rainbow when seen near the horizon. 

Stars shine by their own light. But planets 
are really dark bodies. They shine only by the 
reflected light of the sun, as our moon does. 


BIRD’S-EYE VIEW OF THE SOLAR SYSTEM 23 


The reflected light is much fainter and less 
dazzling than direct light. If the planets were 
as many million miles away as the stars they 
would be completely invisible. It is because 
they are so much closer to us that their light 
seems as bright as that of the brightest stars. 
Our earth, seen from the other planets, would 
be like a star, too. 

Besides the earth, there are seven other planets 
in the sun family. The earth’s oldest brother 
is Mars. Her youngest is Saturn, unless we 
consider the newly discovered Pluto, about 
which astronomers are rather uncertain. 

The names of the eight planets, starting with 
the nearest to the sun and moving outward to 
the next nearest and so on, are as follows: Mer¬ 
cury, Venus, Earth, Mars, Jupiter, Saturn, 
Uranus, and Neptune. Here is an easy way to 
remember the order in which they come. Sepa¬ 
rate the first letter of their names from the rest 
of the word. Then add new letters to the first 
letters so as to make new words. The next step 
is to form a sentence. You may want to make 


How many 
planets 
are there? 


2 4 


OTHER WORLDS THAN THIS 


your own sentences. But here are two ready¬ 
made, just in case you do not: 

M-ark’s V-exed E-mployer M-ade J-ohn S-tay 
U-ntil N-oon. 

M-any V-icious E-lephants M-ove J-ungles 
S-eeking U-nfriendly N-atives. 

Mars and Mercury both begin with M, it is 
true. But it is easy to remember why the planet 
nearest the sun was called after the winged 
messenger of the Gods. He travels around the 
sun in a much shorter time than any of the 
other planets. He takes only eighty-eight days. 
That means that his year is only as long as two 
and a half months of our year. Of course, he 
hasn’t as wide a circle to travel around the sun, 
for he is only a third of the distance from it 
that we are. Stand a yard away from a tree 
and run around it. You will find that it takes 
much less time to get back to your starting place 
than if you stand three yards from the tree and, 
running at the same speed, keep three yards 
between you as you circle about it. 

To get a clear picture of the differences in 


BIRD’S-EYE VIEW OF THE SOLAR SYSTEM 25 


size and distance of the planets, let us imagine 
we are going to build a miniature Solar System. 
Find a globe of the earth in the schoolroom 
and use this to start with. The earth is actually 



If you are only a yard from the tree it ta\es less time 
to run around it 


over a hundred million times larger, because 
the globe is only half-a-foot high. 

We figure that our sun, in relation to the six- 
inch earth, is going to be as high as a four-story 
building, fifty-four feet. So it is necessary to 
build our miniature Solar System in the school 
yard instead of in the classroom. Someone has 
a tennis ball, and that will represent Mercury. 


How big are 
the planets? 





















26 


OTHER WORLDS THAN THIS 


Venus is another globe about the size of the 
earth, a baseball is what we want for Mars. A 
golf-ball will do for the moon. Jupiter is the 
first of the larger planets we are to meet. 
He is the biggest of them all, as a matter of fact. 
We must use a globe as tall as a man for him. 
Saturn is about the height of a boy ten years old 
(four and a half feet). But the rings around 
him occupy a foot and a half more. Uranus is 
about the size of a medicine ball (two feet in 
diameter). Neptune is two and a half inches 
higher. The moons of the other planets re¬ 
quire several more tennis and golf balls, some 
marbles and a few grains of sand. 

Now that all the members of the Solar 
System are lined up the next thing is to place 
them the correct distance from each other and 
from the sun. Our four-story sun has already 
been placed in the middle of the school yard. 
We can leave it where it is and turn our atten¬ 
tion to Mercury. The tennis ball that represents 
Mercury is over a hundred million times smaller 
than the real Mercury. All the other objects 



This map gives an idea of the distances of the various 
planets from the sun 


27 




















28 


OTHER WORLDS THAN THIS 


used for planets are also a hundred million times 
smaller than the planets they represent. This 
being the case, we must reduce the distances 
between the planets over a hundred million 
times as well. Otherwise our miniature Solar 
System will not be a true model of the real 
Solar System—in perfect scale. Bearing this 
in mind, we quickly discover that it is going to 
be impossible to confine our miniature system 
to the school grounds. Mercury, the nearest 
planet of all, must be placed over a third of 
a mile away. Venus is going to be almost 
four-fifths of a mile distant. The earth is a mile 
and one-tenth distant, with the moon fifteen 
feet to one side of it. Mars is approximately a 
mile and a half from the sun. Jupiter is about 
six miles. Saturn is ten miles and Uranus and 
Neptune are twenty and thirty miles away. 

We can tell by this that even so tremendous 
a sun as ours is dwarfed into nothingness by the 
four billion miles that extend from its heart 
to the outermost limits of the Solar System. 


Chapter III 


SECRETS OF THE SUN 

T HOUSANDS of years ago when anyone 
asked, “What is the Sun?” people an¬ 
swered, “The sun is the golden chariot of the 
sun-god. The sun-god drives across the heavens 
every day. He pursues the beautiful goddess 
of night. But he can never overtake her. She 
is swifter than the wind.” 

Today when anyone asks this question they 
are told, “The sun is the father of the earth. 
A tremendous ball of fiery hot gases. More 
than one million times as big in volume as the 
earth. And more than ninety-two million miles 
away. A glorious shining body around which 
the earth and the other planets revolve. The 
source of light and heat and life.” How much 
grander is our idea of the sun today! And how 
much greater is our knowledge of it! In the 


29 


3° 


OTHER WORLDS THAN THIS 


What is the sun 
made of? 


How do we 
\now the sun 
is made of gas? 


last hundred years astronomers have forced 
many of the sun’s secrets from him. They have 
thus succeeded in painting a picture, that is a 
thousand times more like the sun than any 
portrait made of him before. 

The sun is a fiery mass of metals and 
elements. Metals such as iron, nickel and 
aluminum, and elements like hydrogen, oxygen 
and helium. The heavier metals and elements 
are towards the heart of the sun. The lighter 
ones float around in clouds over its surface. 
Strange as it may seem, even the heaviest metals 
are in the form of gas. It is hard for us to 
imagine a gas of lead, platinum or gold, because 
we have never seen such a thing. As a matter 
of fact, there are few furnaces on earth hot 
enough to melt metals into gas. 

We know the sun is made of gases for many 
reasons. But a most important reason is the 
fact that as it turns on its axis, some parts of it 
move faster than others. If the sun were as 
solid as the earth and not made of gases this 
could not possibly occur. 


SECRETS OF THE SUN 


3i 


No one has ever seen the inside of the sun. 
But we know it is even hotter than the outside 
and the gases are thicker and denser. Toward 
the heart of the sun they have become so thick 
and heavy as to be much denser than water. 

Next to this inner mass of gaseous material 
that astronomers know little or nothing about, 
is a region they have called the photosphere or 
lightsphere. It is made of lighter gases and is 
almost white in color. On top of the photo¬ 
sphere is a layer of gas almost ten thousand 
miles thick. It is called the photosphere or 
chromosphere, because it looks like a scarlet 
fringe of leaping flames. The tongues of flame 
reach up for thousands of miles. Some of the 
largest of them are actually eruptions. The 
outermost layer of the sun looks like a silver 
halo. It gradually fades into the dark stretches 
of ether. This is the reason it has been called 
the crown or corona. 

The sun is made chiefly of materials found 
on the earth, although there may be elements in 
the sun that we know nothing about down 


Is the sun the 
same on the in¬ 
side as on the 
outside? 


Is the sun made 
of the same stuff 
as the earth? 


32 


OTHER WORLDS THAN THIS 


here. It is possible that in years to come some¬ 
one may discover them, just as helium was once 
discovered. Helium was found in the sun long 
before it was known to be on earth. Since no 
one had anything with which to compare it, it 
was called helium, from the Greek word for 



The outermost layer of the sun loo\s li\e a silver halo 
and is called the corona 


sun. Helium is what many dirigible airships 
and giant balloons are filled with. It is the next 
to the lightest gas we know anything about. 
And it will not explode. There is more than 
enough helium in the sun to float an airship as 
large as the earth. There is enough aluminum 
to make a kettle big enough to hold the moon. 
The amount of silver in the sun is sufficient to 








SECRETS OF THE SUN 


33 


build a city the size of New York. And the 
great mass of iron would fill up our oceans to 
the brim if it could be poured into them. These 
as well as gold, mercury, and oxygen are among 
the forty or more elements that are found in 
the sun. 

We know that the temperature of the sun is 
very high. It is probably ten thousand degrees 
above zero at the surface. This is thousands of 
degrees higher than the hottest fire or furnace 
on our earth. If there were giants in the world 
and one of them chose to pick up the earth and 
throw it into the sun, the earth, skyscrapers, 
rocks, mountains and everything would melt 
into thin vapor in less than four hours. When 
we realize that the sun has been almost as hot as 
this, if not just as hot, for millions of years, we 
naturally wonder what makes it so hot as well 
as why it does not cool off. 

To find the answer to these questions we 
must first learn something of atoms and elec¬ 
trons. We have already learned that the sun 
is made of tiny particles of matter, like a fog. 


How hot is 
the sun? 


What ma\es the 
sun so hot? 


34 


OTHER WORLDS THAN THIS 


These particles are made of still tinier particles 
called atoms. An atom is so small that no one 
has ever been able to see one. Even the strong¬ 
est magnifying glass in the world will not bring 
it to light. In one pin point there are several 
thousand atoms crowded together. And there 
are as many atoms in a golf ball as there would 
be golf balls in the earth if the earth could be 
filled like a gunny sack. 

Small as the atom is, it can be divided into 
something still smaller. This “something still 
smaller” is known as an electron. Electrons are 
of two kinds; positive and negative. An atom 
is made up of both kinds. And there are just 
as many negative electrons in an atom as there 
are positive. 

The negative electrons hold in the positive 
ones and prevent them from escaping or turning 
into electricity. They surround the bundle of 
positive electrons like the sugar coating on a pill 
or like guards around a prison wall. 

The atom is perfectly safe unless something 
happens to destroy the balance of positives and 


SECRETS OF THE SUN 


35 


negatives, or unless it is broken down by out¬ 
side pressure. Ordinarily when an atom is 
broken down the electrons will go off in pairs; 
one positive and one negative, like prisoners 
handcuffed to their jailers. If they don’t cancel 
each other (after the manner of an immovable 
object meeting an irresistible force), they will 
combine with other positive and negative elec¬ 
trons and form another atom. 

But occasionally when an atom is disrupted 
there will be a head-on collision of a positive 
and negative electron. The positive will bury 
itself deep in the negative, like a hand grenade 
sinking into a shell-hole. What happens next? 
Both the positive and negative electrons dis¬ 
appear. In their place is a lot of liberated 
energy in the form of light and heat. 

Now let us return to the sun and the reason 
why it is so hot. The sun is made of gases. 
But these gases are much thicker in the interior 
of the sun than on the surface. This is because 
they are made up of heavier particles than the 
lighter gases, particles with more atoms in them. 


Why doesn't the 
sun cool off? 


36 OTHER WORLDS THAN THIS 

According to the law of gravity, heavier or 
larger particles have more pulling power than 
smaller particles and so they are generally in 
the thick or heart of things. In the case of the 
sun, the force of gravity is so great that it makes 
the separate particles in the heavier gases very 
heavy indeed. When they strike one another, 
as frequently happens, they exert a tremendous 
pressure. This pressure is sufficient to break 
down the atoms. And in breaking down the 
atoms, negative and positive electrons are re¬ 
leased. As we know, these often collide head- 
on into one another and transform themselves 
into what astronomers call radiant energy or 
light and heat. 

The law of gravity is a law that is always in 
operation and as far as any one knows always 
has been. So the atoms in the sun are con¬ 
stantly being broken up. But most of them 
recombine. Thus in a billion years or more 
there is very little change in the number of 
atoms in the sun. Those that do go off in light 
and heat are replaced by the stray particles that 


SECRETS OF THE SUN 


37 


the sun is constantly picking up as it travels 
through the great zones of space. Like all the 
other stars our sun feeds upon these stray 
particles “in exactly the same sense that cattle 
feed upon the grass of the fields.” 

We find here the reason why the sun has not 
cooled off during the lifetime of our earth. For 
the same reason it is not likely to die away or 
grow much cooler for billions of years hence. 

An eclipse of the sun is the hiding of the 
sun’s face by the moon. About twice a year the 
face of the sun is hidden from the earth in this 
way. The moon passes between the sun and 
the earth and shuts off the sun’s light. The 
moon is apparently big enough for the sun to 
hide behind. Actually the sun is many times 
too big to be hidden by the moon. It is only 
because the moon is so near us that it is able 
to screen us from the sun. 

Hold a book at arm’s length before you, so 
that it conceals any object you choose to cover— 
lamp, desk, or teacher at the other end of the 
room. You will see in an instant how a small 


What is an 
eclipse of 
the sun? 


3» 


OTHER WORLDS THAN THIS 


Where can a 
total eclipse 
be seen? 


What does an 
eclipse of the 
sun loo\ li\e? 


object can hide a large one if the large one is 
far enough away. 

A total eclipse of the sun can be seen on only 
a small part of the world at one time. And 
since the eclipse is likely to be anywhere, one 
year Alaska, the next Africa, observers of 
eclipses must often travel great distances to see 
them. A man may travel two months to get 
to the best spot on the earth from which to 
observe a total eclipse. He may have spent 
twenty years collecting the money to pay the ex¬ 
penses of his journey. But the eclipse will last 
for only eight minutes at the most. More likely 
it will last for only three. Possibly it will be a 
cloudy day. Then he will not be able to see it 
at all. Why then, are astronomers so ready to 
risk time, money and even health for a few 
seconds of observation? What is there about a 
total eclipse of the sun that is so strangely 
fascinating? 

In the beginning an eclipse of the sun is like 
the darkening before a summer thunder-storm. 
Gray shadows gradually spread over the land- 



At this moment in the eclipse the leaping flames of the 
sun’s color-sphere are faintly visible 


39 














4° 


OTHER WORLDS THAN THIS 


scape. Small animals hurry to shelter. The 
mother-hen drives her chickens into the coop 
and covers them with her feathers. A dog 
whines in terror. Birds fly restlessly from tree 
to tree, afraid and yet unwilling to believe their 
day is suddenly come to a close. As the sky 
darkens, their twittering ceases, and cautiously 
they find the way back to their nests. The 
fading of the light is slow and measured until 
the sun, half covered by the moon, is only a 
golden crescent. Then darkness sweeps in like 
the wind. The crescent sun becomes paler and 
thinner, a delicate thread of light one can look 
at steadily with the naked eye. This sudden 
darkness is alarming. It changes the color of 
everything. The grass and trees seem sickly— 
the line of the sky where it touches the earth 
changes from yellow to a greenish gray. We 
look at our friends. Their faces are ashen, like 
the faces of dead men. 

Our sun is now only a flash of light that snuffs 
out like the lightning. In an instant it gives 
place to a halo of mysterious radiance, shooting 


SECRETS OF THE SUN 


4i 


outward in icicle-shaped flashes. At this 
moment, too, the leaping flames of the sun’s 
color-sphere are faintly visible. They encircle 
the outer edge of the halo like a pink afterglow. 

Mercury, Venus, and the few stars close to 
the sun shine with the brilliance of night. This 
is the moment of moments, that miraculous 
second for which the astronomers have been 
waiting. But what are they doing? 

Are they standing spellbound, fixed in their 
places? No indeed. All of them are moving 
around, busy with a hundred seemingly trivial 
tasks. Some are drawing diagrams, others 
making calculations. Many are working with 
their telescopes. A few are looking into spec¬ 
troscopes. Almost all of them are either taking 
photographs or making notes. 

During an eclipse of the sun things can be 
seen that can never be seen at any other time, or, 
at least, not half so well. The sun’s halo, or 
corona, is visible only during a total eclipse. 
The giant flames of the color-sphere are never 
so well defined as at this moment. Mercury, 


What do the 
astronomers do 
during a 
total eclipse? 


Why are 
astronomers 
interested in 
eclipses of 
the sun? 


4 2 


OTHER WORLDS THAN THIS 


the planet nearest the sun, is seldom seen very 
clearly at any other time. Mercury travels 
across the sky during our day and so it is out¬ 
shone by the sun except for a brief period at 
sunrise and sunset. 

In like manner, the stars that appear only in 
the daytime, or close to the sun, are generally 
outshone by the sun. An eclipse gives them 
a chance to introduce themselves. 

Thus we learn from eclipses where the stars go 
in the daytime and what the heavens would be 
like if our day and night came at opposite times. 
From the observation of eclipses, astronomers 
have learned many of the sun’s most important 
secrets: What the sun is made of, for example; 
how big it is; how dense it is; what its atmos¬ 
phere is like; and what is in its neighborhood. 


Chapter IV 


A TRIP TO THE MOON 

T HE fact that no one has ever visited the 
moon need not prevent us from undertak¬ 
ing an imaginary trip there. Lucian, Fonta- 
nelle, Jules Verne, Abbe Moreux, Sydney Tur¬ 
ner and Francis Godwin have given us author¬ 
ity for such a flight of fancy. After the journey 
we are about to make it may interest you to 
revisit the moon with the authors just men¬ 
tioned. Once you have made the trip, all you 
will need in preparation are their books: Above 
the Clouds, Conversations on the Pluralty 
Worlds, From the Earth to the Moon, A Day 
on the Moon, A Voyage Through Space, and 
The Man in the Moon. 

The moon is our nearest neighbor. When 
closest to the earth it is only 221,000 miles away. 
Travelers like Burton Holmes have gone even 


How jar away 
is the moon? 


43 


44 


OTHER WORLDS THAN THIS 


What does the 
earth loo\ li\e 
from space? 


greater distances, though not at one time. The 
earth is not quite 25,000 miles around. Flying 
continuously the Graf Zeppelin could circle the 
globe in 26 days, 12 hours, not counting stop¬ 
overs; an average rate of 50 miles an hour. For 
our trip to the moon, however, suppose we 
choose the airplane that won the Schneider Cup 
Race. It holds a record of 337 miles an hour, 
but a rate of 300 miles would be a safer average 
to count on. Traveling at this speed, with no 
stops, we would reach the moon after four 
weeks and three days in transit. 

For days we have been steadily looking back¬ 
ward toward the earth while our pilot steers 
his craft straight ahead. We are fascinated by 
the strange sight of our earth growing smaller 
and smaller as it fades into the distance. No, 
fading is not the right word. After we have 
gone so far that we can no longer see the sepa¬ 
rate continents, the oceans and the polar cap, 
we notice that the earth is becoming luminous. 
It shines against a jet black curtain of space 
like a giant street lamp. Is it burning up? 


A TRIP TO THE MOON 


45 


Then someone assures us that everything is 
all right. The earth is only reflecting the sun’s 
rays, as other planets and the moon do. But 
who would believe the earth could be so beau¬ 
tiful? We look toward the moon. It seems 
unimportant in comparison. As the days go 
by, however, the moon grows more interesting. 

We give up looking toward the earth, which is 
now only a lighted globe, and direct our at¬ 
tention to the moon alone. * 

For amusement we study a miniature globe What is a globe 
of the moon. We are interested to discover a moon 

strip from pole to pole, a little less than a half 
of its area, entirely blank. This is because 
astronomers on earth have never been able to 
see this section of the moon. Our satellite, as 
it happens, turns only one side of its face towards 
the earth. Fortunately, astronomers have been 
able to see a little more of its surface than just 
this one-half. Slight variations in the rate of 
its revolution give short glimpses of the other 
sections. What it is possible to see on the globe 
proves unusually fascinating. Enormous moun- 


4 6 


OTHER WORLDS THAN THIS 


What i 
li\e? 


tains and chains of mountains, vast craters, 
gigantic canyons, and tremendous plains! 

Everything has a name. We recognize most 
of the names as belonging to famous earth-men, 
astronomers and philosophers. Aristotle, Plato, 
Herodotus, Copernicus, Ptolemy, Kepler, Leib¬ 
nitz, and Grimaldi are all included, some be¬ 
cause they discovered the objects their names are 
attached to, others because of their interest in 
astronomy or their financial support. We name 
parts of our earth in the same way; America, 
Washington, Pikes Peak, Pennsylvania, Vir¬ 
ginia, Carolina, for example. 

It may be well to interrupt our journey at 
this point. Let us pause to thank fortune we 
are not undertaking an actual trip to the moon. 
Imaginary travels have some very real advan¬ 
tages. Take our present journey from the 
earth, through space. The temperature of space 
is 450 degrees below zero. And since it does 
not reflect light it is pitch black as well. 
space The earth’s atmosphere extends less than 
three hundred miles upward. This means that 



Our moon turns only one side of its face toward the 
earth—the other is invisible 


47 












4 8 


OTHER WORLDS THAN THIS 


What is the 
surface of the 
moon li\e? 


beyond it there is no air to breathe. And sound 
does not exist. A person actually attempting 
such a journey would discover that the fastest 
airplane could not move one inch through space 
unless it was surrounded by some sort of atmos¬ 
phere through which the propeller could thrust 
its way. Since the force of the earth’s gravity 
extends far beyond its atmosphere, the airplane, 
supposing it could reach such a point in space, 
would gradually slip toward the earth, falling 
faster and faster the closer it came. Its attempt 
to fly to the moon would be a failure. In the 
meantime our aviator would have suffocated, 
provided he had not frozen to death first. 

When we are about 23,000 miles from the 
moon, approximately the distance around the 
earth, the speed of our plane increases to a 
marked degree. Our pilot cuts off the motor, 
and we glide peacefully forward. We are now 
at a point where the attraction of the moon is 
greater than that of the earth. The moon is 
gently pulling us toward her. The nearer we 
get, the faster we go. 


A TRIP TO THE MOON 


49 


Now we can plainly see her dark plains and 
bright mountain tops. Some of the moun¬ 
tains lie in gigantic chains, extending for 
hundreds of miles. Their peaks are as tall as 
the peaks of our highest mountains. But they 
look much bigger because the moon is very 
small in proportion. The mountain chains are 
cut by tremendous gorges, deeper than the 
Royal Gorge and by valleys so thin they look 
like slits. Vast plateaus and plains, at one time 
thought to be seas, cover a large part of the 
moon. From their midst and along their edges 
rise mammoth craters. Many of these craters, 
or cup-shaped cavities, have walls three or four 
miles high. From our position just above the 
moon they look like pock-marks on its face. 
The surface is rough, grim, and forbidding. 

Our pilot signals that he intends landing in 
Copernicus, because the surface to the north of 
its central mountains is remarkably smooth and 
free of craterlets. Copernicus is one of the 
biggest and best known of the lunar craters. 
He circles around it, a distance of almost 176 


50 


OTHER WORLDS THAN THIS 


What is the 
climate of the 
moon? 


miles. The walls are almost two miles high. 
A lofty mountain, twenty-four thousand feet 
from the plain to the tip of its topmost peak, 
rises from the center. It looks for all the world 
like a collection of ice cream cones on a giant 
platter. 

Suddenly the rocky surface of the moon rises 
up to meet us. Here, at last, after a month’s 
journey we are on the moon. We get out to 
stretch and sniff the air. Only there isn’t 
any air, and we can’t sniff. The icy arms 
of space encircle the moon. We make the 
sad discovery that the moon has no atmosphere 
whatever. This means that it never rains on 
the moon. It never snows. Rainbows are im¬ 
possible. Sunrise and sunset are without colors, 
other than primary. The sky is neither blue nor 
grey, nor any shade at all but black. With 
no atmospheric blanket to protect it from the 
sun’s rays, the naked rock-surface of the moon 
is heated to the boiling point. In the blinding 
glare, objects of the lunar landscape have the 
sharp edged look of white silhouettes. 


A TRIP TO THE MOON 


5i 


The sun has never seemed so brilliant or so 
blue. And yet stars can be seen up to its very 
rim. There must be several thousand more than 
are visible on earth. The heavens are crowded 


What does the 
sky look ^K e 
from the moon? 



Many of the cup-like craters of the moon have walls 
that rise two miles high 


with them. It is a magnificent sight. But the 
most interesting object of all is our own planet, 
the earth. It sways slightly to and fro over our 
heads and seems as big as a basket ball. The 
light from the earth is far greater than the 





52 


OTHER WORLDS THAN THIS 


How jar could we 
see on the 
moon? 


brightest moonlight on a Californian moun¬ 
tain-top. It is forty times as bright. The sight 
of it makes us a little homesick. So we turn our 
attention to other things. 

How strange that we can see for only such a 
short distance! The walls of the crater are 
quite invisible unless the sun is shining directly 
upon them 

But we know they are there, for we have just 
seen them. Our pilot tells us that the reason 
we can see no farther is because the moon is 
so much smaller than the earth. Objects any 
distance from us are on a curve below our line 
of vision. If the earth were one-fourth as large 
as it is, or as small as the moon, we would see 
the masts of ships disappear when they were 
only six miles out at sea instead of twelve. 

Turning suddenly, we are astonished to find 
our fellow travelers leaping high into the air. 
Apparently they do this with the greatest ease. 
We take a step toward them and find ourselves 
doing the same thing. There was never a 
pleasanter sensation, the steady slow ecstasy of 


A TRIP TO THE MOON 


53 


motion one dreams about only to waken and 
find one has fallen out of bed. Jumping clear 
over the heads of one’s friends is no trick at 
all. Unless they are attempting to jump over 
somebody else at the same moment. Anyone 
who has ever seen a slow-action motion picture 
will have a good idea of the strange appearance 
these leaping earthmen present. 

Moon magic is not the name for this delight- Is there moon 
ful buoyancy. But the law of gravitation is. ma s ic? 
Because the moon is smaller than the earth and 
because it is made up of lighter particles, its 
pulling power is only one-sixth that of the earth. 

Fortunately, the force of gravity depends on 
density as much as on size. 

Here are a few of the things we could do on 
the moon. We could strike a baseball so that 
it would reach a fielder almost one-third of a 
mile away. We could lift a horse. We could 
jump over a rock as high as a three story house. 

We could throw an apple up in the air and 
easily fill it with darts before it would touch the 
ground. Or we could play a game of tennis 


54 


OTHER WORLDS THAN THIS 


What is a night 
on the moon 
like? 


with a net thirty feet high and a court the size of 
a football field. During our month’s stay on the 
moon we have plenty of opportunity to do all 
these things. But the novelty soon wears off. 

In the course of time we discover another 
strange thing about the moon. Its month and 
its day are exactly the same length! Imagine 
a day two weeks long! And a night two weeks 
long! The setting of the sun occupies one-half 
of an entire earth day. And another twelve 
hours is required for the sun to rise. With the 
coming of night, intense cold sets in and a dark¬ 
ness like that of midnight. There is no such 
thing as twilight, because of the moon’s lack 
of an atmosphere to reflect the lingering rays 
of the sun. And there is no such thing as a 
temperate heat or cold, because a protective air- 
blanket is missing. Two hours after sunset the 
moon’s temperature has fallen below the freez¬ 
ing point. Forty-eight hours later it is almost 
one hundred degrees below zero, even colder 
than Byrd found it at the South Pole. This in¬ 
tense cold continues until sunrise the following 


A TRIP TO THE MOON 


55 


lunar day. The reason for the long lunar night 
and day is this: As the moon travels around 
the sun, it turns very slowly on its axis. One 
side of it is thus exposed to the rays of the sun 
for a great length of time. 

During the long lunar night we occupy our¬ 
selves by watching the earth, sometimes with 
a telescope, sometimes without. We see the 
earth rotating on its axis overhead. Through 
the telescope we can distinguish its oceans and 
continents. They move from west to east and 
around again, endlessly appearing and disap¬ 
pearing. We notice too that the surface of 
the earth is almost hidden by clouds. They 
swirl and eddy before the wind in the most 
engaging fashion. Parting here and there they 
reveal a strip of green forest or ocean. 

Although we cannot see the sun, we are able 
to see its effect on the earth. Sunrise and 
sunset progress in orderly fashion around the 
globe. Darken the schoolroom, then get some¬ 
one to direct a flashlight at a globe of the earth 
revolving from west to east. Now walk slowly 


Why does the 
moon change 
from crescent to 
full moon? 


56 


OTHER WORLDS THAN THIS 


What are the 
scenic wonders 
of the moon? 


around the revolving globe, west to east, as 
the moon does. Then you will see just how the 
earth changes from full earth to three-quarters 
earth, to half earth, to quarter earth, to no 
earth, to new earth, to half earth, and all over 
again. In other words, the earth as seen from 
the moon goes through the same phases that 
the moon does as seen from the earth. The 
constantly changing appearance of the moon 
is due to its constantly changing position in 
respect to us and the sun. There are times 
when the moon is quite invisible because the sun 
is shining on the side we never see. When 
there is a full moon, it is shining only on the side 
facing us, and when there is a half moon, it is 
shining partly on the side we do see and partly 
on the side we don’t see. 

We wait until the sun is well overhead before 
taking our departure from Copernicus. Before 
leaving the earth’s satellite, we intend making 
a short inspection of its scenic wonders. And 
we want to be able to see them in the best light 
possible. Rising from Copernicus, then, we 


A TRIP TO THE MOON 


57 


travel in our airplane north across the so-called 
sea Imbrium (Sea of Showers) to the Crater 
Plato. The walls of Plato rise as high as seven 
thousand feet in some places and surround a 
pit bigger than the state of Delaware. 

From Plato we fly south and to the right 
until we reach Aristarchus. This is indeed a 
glorious sight, the most brilliant crater on the 
moon. It is with some reluctance that we leave 
it for Grimaldi. Grimaldi, we are told, is the 
darkest lunar object of its size. But when we 
finally get there, we are more than glad to have 
come. This somber crater is so gigantic that 
it could easily contain the entire kingdom of 
Denmark. Skirting one side of the plateau, 
Mare Humorum (Sea of Vapors), we pass over 
the crater Gassendi on our way south to Tycho. 
Gassendi is only interesting for the many 
crevices in its walls, so we waste no time over 
it. Tycho, on the other hand, is a magnificent 
crater over fifty miles wide and nearly three 
miles deep. A mountain more than a mile high 
rises from its center. 


Are there people 
in the moon? 




58 OTHER WORLDS THAN THIS 

Following a closed crack in the moon that 
runs out from Tycho and extends for hundreds 
of miles north, we are led directly to the crater 
Theophilus. Theophilus is the deepest crater 
in the moon, almost four miles deep. In the 
center of Theophilus are three lofty mountains 
well over three miles high. Their altitude is 
so overpowering that we are glad to be flying 
still farther north to the Sea of Serenity. From 
the left edge of Mare Serenitatis, the Apennine 
Mountains jut out. They point directly to 
Copernicus. Back at Copernicus, we waste no 
time, but depart immediately for the earth. 

Of course, all of us know there is no such 
thing as the man or the woman in the moon. 
But the question naturally arises, “Are there 
people of some sort living up there; is our beau¬ 
tiful satellite inhabited?” It is, perhaps, just 
as well to decide this question for ourselves, 
since our recent visit has made us familiar with 
the moon’s climatic conditions. Whatever we 
decide, we need never deprive ourselves of the 
fun of finding the man, woman or hare in the 


moon. 


A TRIP TO THE MOON 


59 


Unless you were born in the Far East you 
have probably never heard of the hare in the 
moon. It seems, according to a Hindo legend, 
that Buddha in an early incarnation had the 
appearance of a hare. His best friends were 
an ape and a fox. One day, as they were walk¬ 
ing together, they met the great God Indra dis¬ 
guised as a beggar. He asked them for food. 
Very willing they all set out to get him some. 
The fox and the ape each returned with a 
generous supply of choice morsels. The hare 
was not so successful. He came back empty- 
handed. Not to be outdone in hospitality, he 
built his guest a fire and threw himself into the 
flames, thus offering himself for the roast. 
The God Indra was so touched by this sign of 
devotion that he granted him eternal life and 
placed him in the moon. If there is a full moon, 
and you look very carefully in the center of it, 
perhaps you will be able to see him now. 

The man in the moon is much easier to see. 
But the most that can be said for him is that he 
is not handsome. Besides, he has a bad repu- 


What about the 
hare in the 
moon? 


What about the 
man in the 
moon? 


6o 


OTHER WORLDS THAN THIS 


What about 
lady in the 
moon? 


tation. The story goes like this: A fairy 
wandering aimlessly over the countryside one 
Sunday morning came face to face with a man 
carrying a load of sticks. “Why do you work 
on the Sabbath?” said the fairy quite sternly. 
“Sunday on earth or Monday in heaven, it’s all 
the same to me,” said the man. At this the 
fairy grew very angry. “Then carry your 
bundle forever” she cried. “You shall never 
see a Sunday again. From now on you are 
going to travel with the moon where it is always 
Monday.” (Moon-day.) 

the The lady in the moon is plainest of all to see. 
Once you have found her, it is hard to see either 
the man or the hare. She looks like a Gibson 
girl with a pompadour over her forehead. But 
she is much older than the Gibson girls, older, 
in fact, than the very first girl on earth. In 
ancient Peru, the Indians said she was a beau¬ 
tiful Inca maiden that had fallen in love with 
the moon and had thrown herself into his arms. 


Chapter V 


OUR NEAREST NEIGHBORS. 

T HE earth’s nearest neighbors are the 
planets Mercury, Venus, and Mars. They, 
and the earth, are known as the terrestrial or 
minor planets. This is because they are the 
smallest planets in the Solar System, as well as 
the ones nearest the sun. Compared to Jupiter, 
Saturn, Uranus and Neptune, they are very 
close together. The entire group could sit 
comfortably between any two of the bigger 
planets and still leave room for another group 
just as broad. If we think of the distance 
between the sun and the frontier of the Solar 
System as a highway one mile long, the earth 
is one-thirtieth of a mile along the road. Mars 
is a twentieth the distance, or five per cent. 

The terrestrial planets may be classified as 
minor, but they have at least one outstanding 


61 


62 


OTHER WORLDS THAN THIS 


Which planet 
is smallest? 


How does Mer¬ 
cury lool{ from 
the earth? 


feature. They are near enough to the sun to 
receive the fullest measure of its light and heat. 

Mercury is a pigmy planet, the runt in the 
Solar family. As we shall see later, it is even 
smaller than one of Jupiter’s moons. It is only 
a half bigger than our moon. Nevertheless, it 
holds the place of honor nearest the sun, the 
inside track in the everlasting race around it. 
On an average it covers a distance of thirty 
miles in one second. Traveling at this rate it 
takes only eighty-eight days to complete its 
circuit. This means that its year is a little less 
than three months long. 

From the earth, Mercury seems like a star 
of the first magnitude. It shines with a 
brilliant white light. But it is seldom seen ex¬ 
cept at sundown and sunrise. Even so, it is vis¬ 
ible for only a short period during the year. 
This is because it is so close to the sun. 

If we were to observe Mercury through a 
telescope night after night, we should see it go 
through the same phases as the moon. We 
should see it pass from new Mercury to quarter 


OUR NEAREST NEIGHBORS 


63 


Mercury, to half Mercury, to full Mercury, and 
so on. And so we know that this tiny planet 
has no light of its own. It is dependent on the 
sun for its brilliance, just like our moon. It is 
like the moon in still another way. 

Mercury keeps the same side toward the ob¬ 
ject it travels around, and as it circles, it turns 
only once on its axis. You remember that the 
moon pivots around the earth while, at the same 
time, it circles the sun. But Mercury pivots 
only around the sun. So the moon’s day and 
month are the same length, while Mercury’s day 
and year are the same. Mercury is a planet 
without a satellite and for this reason it has no 
month whatsoever. 

The consequences of all this are quickly ap¬ 
parent, if we travel with Mercury around its 
orbit. That half of Mercury facing the sun is 
always light. The opposite half, turned away 
from the sun, is always dark. Thus on one side 
is everlasting day. On the other side is everlast¬ 
ing night. Connecting the halves are two in-be¬ 
tween zones like the seams on either side of a 


Why is a day a 
whole year long? 


Is Mercury a 

two-faced 

world? 


What is the 
climate of 
Mercury? 


64 OTHER WORLDS THAN THIS 

ball. These sections have only one night and 
one day during the whole year. Sunrise and 
sunset are both in the east because the sun never 
rises very high in the heavens. It drops back 
to where it came from, rather than completing 
its journey across the sky. Instead of a real day, 
there is a gloomy, all pervading twilight. 

Someone has called Mercury a study in black 
and white, because one-half is dark and one- 
half is light all of the time. It has little atmos¬ 
phere, if any at all. Atmosphere has the won¬ 
derful power of splitting the sun’s white rays 
into different colors. Without it, only simple 
colors, or red, yellow, green and blue, would 
exist. But Mercury’s lack of atmosphere also 
has a very terrible result. It makes this small 
planet boiling hot on one side and freezing cold 
on the other. If Mercury had both a deep and 
dense blanket of air, it might then be protected 
from these extremes of heat and cold. Warm 
winds from the bright side might then sweep 
over the dark side. And cold winds from the 
dark side might blow over the light side. If 


OUR NEAREST NEIGHBORS 


65 


this were the case, and there was plenty of 
water, life in some form might exist. As it is, 
the side toward the sun is forever exposed to its 
burning rays. They beat down upon its sur¬ 
face with an intensity of light and heat from 
four and a half times greater to nine times 
greater than on earth. 

Imagine a mid-summer day on earth, 90 
degrees above zero. Then multiply by four 
and one-half. You get a mid-winter day on 
Mercury, 405 degrees above zero. 

If you are not already fried to a crisp, try 
imagining a day on Mercury six weeks later. 
This baby planet is now thirty million miles 
nearer the sun than it was before. The sun 
looks two and one-half times bigger. It seems 
as large as a small yacht. And it swings directly 
overhead, slowly to the right and then to the 
left, like a pendulum. The rocks and stones 
are sizzling under a temperature of 810 degrees. 
This is well over the boiling point of lead. 
What little water there may have been on this 
side of the globe has quickly turned into steam. 


66 


OTHER WORLDS THAN THIS 


Why is Mercury 
twice as hot in 
summer? 


But during the next six weeks Mercury will 
grow cooler. The sun will gradually diminish 
in size until it seems no bigger than the arms 
of a windmill in motion. 

There must be a reason for these sudden 
climatic changes. Astronomers tell us that they 
are due to the shape of Mercury’s orbit which 
is a long, narrow oval. For a period of forty- 
four days, Mercury plunges toward the sun. 
But it falls in a curve instead of a straight line. 
During this tremendous plunge of fifteen mil¬ 
lion miles it gains considerably in speed. At 
length it is moving thirty-six miles a second, or 
about five hundred times faster than the fastest 
airplane. When it has reached this rate of 
speed, it is ready to swing abruptly around the 
curve of its orbit closest to the sun. If it were 
going much slower, the sun would be able to 
pull it back on to its surface. Once the 
dangerous curve has been passed it gradually 
slows down to twenty-four miles a second and 
it rounds the outer curve at this rate. Then, the 
outer curve having been weathered, the long 


OUR NEAREST NEIGHBORS 


67 


plunge commences all over again. It goes 
without saying that when Mercury is traveling 
its fastest and is nearest the sun, it is much the 
hottest time of the Mercurian year. In like 
manner its coolest hours are reached when this 
baby planet is leisurely rounding the outer 
curve. 

Due to Mercury’s dual nature its peculiar 
orbit affects only its sunward side. The other 
side is lost in a darkness so profound that 
nothing but a change of axis could cause the 
slightest difference. While the sunny face of 
Mercury rises several hundred degrees in a 
period of six weeks, the dark side remains about 
the temperature of space, 450 degrees below 
zero. 

For many people, Venus is the favorite planet. 
Certainly it is one of the most beautiful. Seen 
from the northern hemisphere, it outshines 
every other stellar object in the heavens. Its 
light is sometimes golden, sometimes silver; 
according to the state of the atmosphere. It is 
like a beacon of friendliness, a magnet that 


Which is the 
evening star? 


68 


OTHER WORLDS THAN THIS 


Why is Venus the 
earth’s twin? 


draws all eyes in its direction. Perhaps you 
already know Venus. She is sometimes called 
the morning star, and then again, the evening 
star. Like Mercury, Venus is so close to the 
sun that she makes her appearance with it. She 
is much nearer the earth than Mercury. And 
she is several times larger. So she appears much 
brighter and more beautiful. Unfortunately, 
Venus is an infrequent visitor. Between her 
disappearance and her return there is a long 
period of a year and seven months. During 
this time she has been traveling so close to the 
sun that she is completely obscured by its glare. 

Venus has often been called the earth’s twin. 
An observer from another planet would cer¬ 
tainly think she was. Her light at such a 
distance is no brighter than the earth’s The 
similarity, however, does not rest here. The 
earth and Venus are much the same size. 
Venus, according to recent measurements, is 
only 327 miles smaller in diameter than the 
earth. And her mass is practically the same. 
Moreover, Venus has an atmosphere. This 


OUR NEAREST NEIGHBORS 69 

atmosphere is cloud-laden. This outer layer 
is just above freezing, but the surface may have 
a temperature similar to that of the earth. No 
instrument has ever measured the inner layers. 
It is probably cloudy enough to protect her 
from the double amount of light and heat that 
she gets from the sun. If this is so, the atmos¬ 
phere may contain oxygen as well as vapor. 
Then she is in condition to support life. 

With the stage set for life, and many noted 
astronomers, such as Moulton, incline to the 
belief that it is, more than likely there are living 
beings to act upon it. This being the case, what 
are the Venusians like? And what sort of world 
do they live in? There being no direct evidence 
to the contrary, we can truthfully say that con¬ 
ditions seem favorable for the existence of beings 
somewhat like ourselves. However, we should 
not expect them to be twins with the human 
race. Perhaps they are taller than we earth- 
men. There is a possibility that they could 
support large bodies without discomfort, be¬ 
cause they would weigh less. The force of 


Is Venus 
inhabited? 


7 o 


OTHER WORLDS THAN THIS 


What is the 

Venusian 

climate? 


gravity is fifteen per cent less on Venus than 
on earth. But we must remember that the air 
is thinner and would counteract most of the dif¬ 
ference. Then again, a warm climate usually 
breeds a short-legged race of men. And we 
have reason to believe that Venus is a land of 
perpetual summer. 

As Venus journeys around the sun, she steers 
her course by her axis. The axis—an imaginary 
line running through the north and south poles 
—seems to stand upright on the road of travel. 
Every twenty-four hours, according to recent 
observations, she makes a complete turn around 
it. It would seem as though she were boring 
her way through space like a turning screw. 
With an upright axis, all parts of a globe 
are exposed to the sun’s rays during the day, 
every day in the year. The amount of sun¬ 
light each part gets never varies. This means 
that if Venus does have an upright axis and if 
she does revolve around it every twenty-four 
hours, she has absolutely no change of seasons. 
Where it is winter, it is always winter, and 



If Mars is inhabited, its people can comfortably 
support bodies fourteen feet tall 


71 

























7 2 


OTHER WORLDS THAN THIS 


What would the 
earth loo\ li^e 
from Venus? 


where there is summer it is always so. Under 
such circumstances summer on Venus would 
range from areas of perpetual springtime to 
tropic zones and cover by far the greatest part 
of the globe. If we could stretch the combined 
states of California and Florida like a piece of 
leather to cover a planet the size of Venus, we 
might get a pretty good idea of what her cli¬ 
mate is like. It is safe to say that the garden 
spots on Venus would rival the best that Cali¬ 
fornia or Florida has to offer. Trees would be 
taller, vines would climb higher, and flowers 
would be bigger and brighter in every way. 

Before we let imagination run too far, sup¬ 
pose we investigate Venus’ outlook on the 
world. Astronomers say it is the best in the 
whole Solar System. They take for granted, of 
course, that Venus’ atmosphere is not dense 
enough to hide the heavens. 

Looking out from Venus, the most brilliant 
and by far the most interesting thing in the 
whole night-sky is Venus’ twin sister, the earth, 
and yet, despite its nearness, the earth is never 


OUR NEAREST NEIGHBORS 


73 


as bright to the Venusians as Venus is to us 
earth-men. This is because the earth gets no 
more than half as much sunlight as Venus. 
And its atmosphere being thinner, its powers 
of reflection are so much the less. 

From this distance the moon and the earth 
appear to be a magnificent double star. The 
moon is forty times fainter than the earth. But 
even so, it is more than six times brighter than 
the brightest star. Astronomers on Venus 
would be able to see the side of the moon that 
is turned forever away from the earth. They 
would get an unusual view of an eclipse of the 
sun by the moon. And they would see an 
eclipse of the moon by the earth’s shadow as 
plainly as a movie in a darkened hall. 

As on the earth, Mercury is a brilliant, irreg¬ 
ular morning and evening star. The advan¬ 
tages of being a near observer of Mercury would 
probably be offset by the increased dazzle of 
the sun. Venus’ greatest opportunity for 
observing Mercury would occur during one of 
its transits across the sun. At this time, Venus, 


What do the 
other planets 
loo\ like from 
Venus? 


74 


OTHER WORLDS THAN THIS 


Mercury, and the Sun would be directly in front 
of each other. Venus would thus see Mercury 
silhouetted against the sun and could observe 
in detail its outer hemisphere. In like manner 
our supreme moment for the observation of 
Venus is when Venus is silhouetted against the 
sun and moves like a tiny black beetle across it. 
Most unfortunately for us, a transit of Venus 
occurs at rare intervals of a hundred years or 
more. Few of us will live to see the next one, 
which is scheduled for June 8, 2004. 

If Mercury and Venus were large enough to 
cut off the light of the sun, their transits would 
be called eclipses. The same principle under¬ 
lies both. 

Mars, as seen from Venus, would be a de¬ 
pendable but inconspicuous object in the 
heavens. It would be many times outshone by 
the moon. The other planets would appear 
much the same as they do on earth. 

With such a magnificent outlook on the 
world, we would naturally expect the Venus- 
ians to be great astronomers. But should we 


OUR NEAREST NEIGHBORS 


75 


do so we would deliberately ignore one of the 
few certain things about this planet, her dense 
atmosphere. Venus’ atmosphere is said to be 
anywhere from one and a half to two times as 
cloud-laden as the earth’s. 

We must therefore conclude that the clouds 
which continually hang over the Venusian 
landscape hide the heavens even more effec¬ 
tively than the clouds in our own sky. The 
supposed inhabitants are, in all likelihood, as 
ignorant of the earth as they must be of the 
other planets and the stars. Nor is this all. 
They may never have seen the sun. Instead of 
a sun there is probably a strange, diffused glow 
of unbelievable brilliance. To us it would seem 
as weird and artificial as the lighting for a fu¬ 
turistic stage setting. 

Of all the planets Venus is the best suited 
to bear life. But Mars runs it a close second. 
Seen with the naked eye, it appears to be a 
star of the first order of brightness. It shines 
with a ruddy glow like the embers of a dying 
fire. Sometimes it is very close to us. Then it 


Could men live 
on any other 
planet? 


7 6 


OTHER WORLDS THAN THIS 


How does Mars 
differ from the 
earth? 


completely dominates the firmament with its 
brilliance. Do you wonder that the ancient 
Greeks called it Mars, after their God of War? 

Through a telescope, Mars loses most of his 
threatening appearance. It drops from him 
like a mantle. Behold a beautiful round disk 
much smaller than the earth—greenish blue 
and yellowish red lines swirl around and across 
it. Here is the beauty of a Chinese marble. 

The atmosphere on Mars is many times rarer 
than on earth. Its surface is seldom hidden by 
clouds or fog. An astronomer by the name of 
Lowell was thus able to construct a miniature 
globe of this planet. The globe is wonderfully 
complete in detail. Now and again we read 
in the newspapers about a rocket that is going 
to be shot to Mars. If someone were really shot 
to Mars in a pneumatic tube of this sort they 
would be as well supplied with directions for 
finding their whereabouts as the tourists of 
California are with road maps. 

Mars is a small planet, little more than half 
the size of the earth. Its density is about three- 


OUR NEAREST NEIGHBORS 


77 


fourths of the earth’s. So its pulling power is 
little more than a third the pulling power of 
our planet. A boy weighing one hundred 



Through a telescope Mars becomes a beautiful dis\, 
with greenish blue lines across it 


pounds on the earth would weigh only thirty- 
six pounds on Mars. If Mars is inhabited, its 
people can comfortably support a body fourteen 
feet tall. 

By watching the appearance and disappear- 







78 


OTHER WORLDS THAN THIS 


ance of certain set features on its surface, it was 
discovered that Mars rotates on its axis once in 
every twenty-four and a fraction hours. Day is, 
therefore, about the length of our day. The 
seasons are much the same as ours, too. Take a 
globe of the earth and place it on a chalk line 
representing its course around the sun. You 
will see that the rod running through the axis 
makes one side of an angle. The chalk line 
forms the other side. A globe of Mercury 
placed in back of the earth would tilt toward 
the line of travel with approximately the same 
slant. The earth’s seasons are due to the slant 
of its axis. Since the slant of Mars’ axis is the 
same, his seasons must be the same too. 

But it happens that Mars is forty-eight mil¬ 
lion miles farther away from the sun than the 
earth is. So it travels over a much larger circle. 
Moving very little faster than the earth, it takes 
almost two years to get back to where it started. 
Accordingly, Mars’ year is about two of our 
years. And its spring, summer, fall and winter 
are all nearly six months long. 


OUR NEAREST NEIGHBORS 


79 


When we speak of seasons, we must not for¬ 
get that Mars receives one-half as much sunlight 
as the earth. Its blanket of atmosphere is also 
very thin. So while the days may be fairly com¬ 
fortable, the nights are freezing cold. Even 
at the equator it must be way below zero after 
sundown. 

But it’s an ill wind that blows no one any 
good. The rare atmosphere and bitter cold 
combine to give Mars a glorious view of the 
heavens. Stars seem much bigger there than 
here. And instead of one moon to watch there 
are two, Phobus and Deimos. The horses 
which drew the chariot of the great war god 
Mars were called Deimos and Phobus, so these 
satellites are well named. Phobus, the larger, 
is no more than ten miles wide. Deimos is 
only five or six. 

These baby moons are so close to Mars that 
it takes the nearest only seven and one-half 
hours to circle around him and the other only 
thirty hours and eighteen minutes. 

Both the planets are too small and their pull- 


What is the 
climate of 
Mars? 


What are the 
moons of Mars 
like? 


8o 


OTHER WORLDS THAN THIS 


What are Mars’ 
polar caps 
made of? 


ing power too weak to hang on to an atmos¬ 
phere of any kind. But for the minute let us 
suppose a man could live on Phobus, the larger. 
The force of gravity would be so slight that he 
could easily support a body two-thirds of a 
mile tall. And an ordinary sized man would 
be able to jump a thousand feet into the air. 
Coming down he would float as lightly as a 
feather and touch the ground just as gently. 
According to Astronomer Moulton, a base¬ 
ball thrown horizontally would go all the way 
around this moon. The pitcher would thus 
have time to get a bat and strike at it. “If he 
missed it he could take his three strikes, then 
put on his mask, glove and chest protector and 
catch himself out when the ball came around 
for the fourth time.” 

Through the telescope, Mars presents a star¬ 
tling resemblance to the earth. Around both its 
north and south poles is a polar cap. These 
brilliant white spots spread farther down 
toward the equator as winter sets in. In the 
spring they diminish in size, like a knitted 


OUR NEAREST NEIGHBORS 81 

beret that is being unraveled. At the same time 
a delicate green has been noticed to spread up¬ 
wards from the equator. And the so-called 
canals of Mars grow double. The white polar 
caps or Mars are thought to be made of snow. 
As the spring advances they are believed to 
melt and create a supply of water that irrigates 
the land below. 

The much-talked-of canals of Mars were dis¬ 
covered by an Italian Astronomer named Schia¬ 
parelli. He called them canali, or channels, 
merely on account of their shape. They are 
long, dark lines that are supposed to cover the 
surface of Mars with a fine and complicated 
network. They cut through the dark greenish 
places at one time thought to be seas. They 
intersect the reddish areas or deserts. 

Sometimes they are scarcely visible. At other 
times, especially during the late spring, they 
grow very distinct. Then they are seen to be 
double. 

From which we gather that if these channels 
really do exist, Mars is a planet with very little 


What are the 
canals of Mars? 


82 


OTHER WORLDS THAN THIS 


Is Mars a dying 
world? 


water. The dark green areas once thought to 
be seas must be swamp lands of vast extent. 
The swamps are then watered every spring by 
the melting polar caps and what Schiaparelli 
once called canali are more exactly strips of 
vegetation along the real but invisible canals. 

It is hard to believe that Mars’ complicated 
network of canals may be the result of chance. 
Surely human engineers have had a hand in 
building this wonderful system of irrigation if 
such is what it is. 

Mars is said to be a world “well on in years,” 
a planet much older than the earth. When the 
earth is as old, its oceans will be dried up, too. 
Its atmosphere will be as rare, if not rarer. Its 
mountains and its hills will be worn just as 
smooth. At least, this is the state of affairs 
geologists predict for us. They base their judg¬ 
ment upon the past life of our planet. Once 
there was twice as much water on the earth as 
there is now. The atmosphere was deeper. The 
landscape was rougher and sterner. And the 
climate was mild from pole to pole. Every 


OUR NEAREST NEIGHBORS 


83 


minute the earth is losing a little of its vapor. 
But it is such a very little that millions of years 
will come and go before any real difference will 
be noticed. 

If we could visit Mars perhaps we should see 
a civilization much in advance of ours, a predic¬ 
tion of things to come. 

Let us be thankful that the day has not yet 
arrived when a vast swamp connects America 
with Europe. If water is going to be so scarce 
as to make water-sports a crime let us hope that 
the human race will be extinct. We may well 
pity Mars. 

Compared to what Mars may once have 
been, it is a pitifully dry, hopelessly barren, 
dying world. Perhaps the Martians look toward 
our beautiful earth with envy. Perhaps they 
have already flashed us signals of distress, hop¬ 
ing that some friendly superhuman effort will 
bridge the tremendous gap of space between us. 


Chapter VI 


OUR BIG BROTHERS 

T HE earth’s big brothers in the Solar fam¬ 
ily are the planets, Jupiter, Saturn, Uranus, 
and Neptune. They are frequently called the 
superior, major, outer, or Jovian planets. Any 
one of them is bigger than the entire group of 
terrestrial planets (including the earth). And 
they are such vast distances apart that the ter¬ 
restrial group could sit comfortably between 
any two of them. 

Let us now return to our solar highway. The 
distance from the sun to the outermost point 
of the solar system is imagined to be the equiva¬ 
lent of one mile. We find Neptune marking 
the end of the mile. It is farthest of all from 
the sun. On the sunward side of Neptune is 
the planet Uranus. It is two-thirds of a mile 
along the highway. Saturn is one-third of a 


84 


OUR BIG BROTHERS 


85 


mile from the sun. And Jupiter, the nearest of 
all the Jovian group, is one-sixth of a mile 
from it. 

In comparison to its big brothers, the earth 
is close to the heart of the solar system. Its view 
of the major planets is little different from the 
sun’s. Is it any wonder that astronomers have 
had such difficulty in learning anything about 
the members of the Jovian group or that we are 
not half as well acquainted with them as with 
the planets, Mercury, Venus and Mars? Does 
it not rather seem a miracle that we know as 
much about them as we do? 

Jupiter is much bigger than any of the other 
planets. He is bigger and heavier than all of 
the other seven rolled into one. If the sun 
suddenly ceased to exist, all the planets would 
be pulled toward Jupiter and would revolve 
around him. If he wished to pass between the 
earth and the moon, Jupiter would occupy a 
third of the distance. Fortunately for the peace 
and order of the solar system, he does not 
attempt foreign travels of this nature. If he 


Which is the 
largest planet? 


86 


OTHER WORLDS THAN THIS 


What are the 
nine moons of 
Jupiter? 


came within walking distance of the terrestrial 
planets, he would kidnap them. They would 
be added to the nine moons he already has. 
Like them, they would have to revolve around 
him as moons. 

The nine moons of Jupiter are among the 
most interesting things about this tremendous 
planet. When Galileo turned his newly in¬ 
vented telescope toward the heavens, four of 
Jupiter’s moons were the first thing he saw. 
They seem to be solid bodies like the earth, al¬ 
though Jupiter himself is slightly denser than 
water, about the consistency of mush. Gany¬ 
mede, the largest moon, is slightly smaller than 
Mars. Callisto, the next largest, is somewhat 
larger than Mercury. Io and Europa, the next 
in point of size, are about as big as our moon. 
The five other Jupiterian satellites range in size 
from one hundred miles across to wee things 
hardly larger than the baby moons of Mars. If 
Jupiter and his satellites were to act out the 
solar system, Jupiter would take the part of the 
sun. The one-hundred-mile planet, being clos- 


OUR BIG BROTHERS 


87 


est to him, would take the part of Mercury. Io, 
as the next nearest, would impersonate Venus. 
Europa would stand for the earth. Ganymede 
would be Mars. And Callisto would be Jupiter. 

Some of Jupiter’s moons travel more slowly 
than others. Others have a much bigger circle 
to cover. So they take different lengths of time 
to go around him. The one that is slowest and 
farthest away requires nearly three years to 
circle around Jupiter. Even so, it moves much 
faster than our moon when it travels around 
us. Instead of one month, a Jupiterian has nine 
types of months to choose from. So according 
to which satellite you prefer to take as a meas¬ 
ure, a month on Jupiter ranges anywhere from 
half a day to nearly three years. 

Speaking of Jupiterians, we should like to 
know if this planet is a fit place for life. Life 
of some sort may exist, perhaps, but not as we 
know it. In the first place, Jupiter is so far 
away from the sun that it gets only a fraction as 
much light and heat. Light twenty-seven 
candles in a darkened room. Then blow out 


Why does 
Jupiter have 
a month half 
a day long? 


Is Jupiter 
inhabited? 


88 


OTHER WORLDS THAN THIS 


all but one. This will show the tremendous 
difference between the amount of sunlight that 
reaches the earth and the amount that reaches 
Jupiter. 



Jupiter as it would appear if it were the same distance 
from earth as the moon 


Of course, Jupiter has a very dense atmos¬ 
phere. In fact, it seems to be all atmosphere. 
If this atmosphere happens to magnify as well 







OUR BIG BROTHERS 


as bottle up the sunshine, Jupiter may be warm 
enough to be lived on. But what of the force 
of gravity? Jupiter’s pulling power is more 
than two-and-a-half times greater than the 
earth’s. A boy weighing one hundred pounds 
on earth would weigh 265 pounds on Jupiter. 
We say on Jupiter, but it is doubtful if he would 
be on Jupiter for very long. He would be in it 
and sinking rapidly toward the center. 

Undoubtedly the rim of Jupiter is composed 
of lighter material than the earth. But it is still 
a matter of dispute whether or not Jupiter has 
a solid core. If it has, then life of some sort may 
exist. Through a telescope clouds of gas and 
smoke are plainly visible on the surface of 
Jupiter. Some astronomers have suggested 
that this may be an overhead blanket that is 
shutting in layers of air. If this is the case, the 
Jupiterians never see the sun at all, even though 
it rises every ten hours. 

Jupiter rotates on its axis faster than any of 
the other planets. Its day is slightly less than ten 
hours long. It makes up for a short day and 


What have 
Venus and 
Jupiter in 
common? 


9 o 


OTHER WORLDS THAN THIS 


Is Jupiter a 
world of ice? 


month by a long year. Traveling steadily over 
its orbit at a rate of eight miles per second, it 
manages to complete a circiut of the sun after 
10,000 Jovian days. This is a little less than 
twelve years of our own time. Like Venus’ 
axis, Jupiter’s is almost upright on its line of 
travel. So there is one long unbroken season. 

Some astronomers believe this one season to 
be winter. Sunshine alone will not warm Jupi¬ 
ter above the freezing point. If it is heated en¬ 
tirely by the sun, the temperature at the surface 
of this planet is about 200 degrees below zero. 
Then there is not, after all, an inner core of 
heavy material, but a core of ice. On the other 
hand, Jupiter may not be heated entirely by the 
sun. Many astronomers believe not. Some say 
it is still in an early stage of planetary growth 
and has still to cool off and become solid. 
Others say it will probably never cool off or 
become solid. 

Certainly the force of gravity on Jupiter is 
very great. The small particles of matter on 
the inside of the planet must be weighted by a 


OUR BIG BROTHERS 


9i 


tremendous overhead pressure. If this pressure 
is great enough to break down the atoms it 
will liberate the electrons just as surely as in the 
case of the sun. In like manner, a few of these 
liberated electrons will be turned into heat, 
while the majority of them will reunite in a 
gaseous form. According to this theory, Jupiter 
must lose a large portion of its mass or bulk 
before it can turn solid. Otherwise the endless 
chain of condensation, terrific pressure, demol¬ 
ished atoms and liberated energy will go on 
forever. The chances are against its getting 
any smaller. More than likely the stray comets 
and meteors that fall onto this giant planet will 
make it bigger than ever before. 

Whatever the real nature of Jupiter, it is 
undeniably one of the most impressive lights in 
our whole night-sky. It appears higher up in 
the heavens than any of the other bright planets. 
And it moves with majestic slowness. For this 
reason it can be seen almost all through the 
night, as well as almost every night in the year. 
By midnight it is usually the brightest spot in 


What does 
Jupiter look like 
from the earth? 


9 2 


OTHER WORLDS THAN THIS 


Who discovered 
Saturn’s rings? 


What do Saturn’s 
rings loo\ like? 


the heavens. No doubt you have seen it. It has 
a golden gleaming yellowish white light. And 
it shines with steady purpose as though to shame 
the flickering stars. Watch for it. And the 
next time you see it, remember that it is a 
gigantic ball of gas and that traveling round 
and round it are nine captive moons, so faint 
as to be completely outshone by their myste¬ 
rious, powerful master. 

Galileo, the noted Italian astronomer first to 
discover the moons of Jupiter, was also the first 
to discover the now famous rings of Saturn. 
Saturn’s rings are quite invisible to the naked 
eye. And since telescopes or spy glasses were 
very scarce in Galileo’s time, very few people 
had any faith in his claim to have seen them. 
They said “It is a flaw in the great astronomer’s 
glass. No other planet has such handles. Why 
should Saturn be an exception to the rule? 
Galileo must be getting old to imagine such 
things.” 

But Galileo was not imagining things, as 
one will quickly discover by pointing a telescope 



Anyone of the great outer planets is larger than the 
entire group of terrestrial planets 


93 


















94 


OTHER WORLDS THAN THIS 


in Saturn’s direction. Under a telescope, Sat¬ 
urn, with its rings plainly visible, presents one 
of the loveliest sights in the whole universe. It 
is a spectacle that once seen will never be for¬ 
gotten. Imagine a glowing ball the color of 
green gold, and around it, circling the equa¬ 
tor, a series of brilliant, silvery white rings. 
These rings are circles of different sizes. They 
fit one inside of another. They are not very 
thick, fifty miles at the very most. But they are 
very broad. The outer edge of the outermost 
ring is thousands of miles from Saturn’s sur¬ 
face. Suppose we could steal the Saturnian 
rings, setting them around our own less for¬ 
tunate globe. They would span a third of the 
distance to the moon. But an easier way to get 
an idea of their breadth is to fly twice around 
the earth following the equator. 

The innermost ring of Saturn is called the 
gauze or crepe ring. This is because it has a 
delicate, almost transparent look. It circles the 
globe at a distance as far from the surface of 
Saturn as San Francisco is from Paris. Its 


OUR BIG BROTHERS 


95 


breadth is equal to the distance between Tokio 
and Lisbon, if one crosses by way of the United 
States. The crepe ring shades smoothly into a 
second ring. This second ring is much brighter 
than the first. It grows increasingly bright 
until, along its outer edge, it is almost more 
brilliant than Saturn itself. The outer edge is 
as sharply cut and as bright as steel. It marks 
a gap in the rings about as wide as the distance 
between New York and Salt Lake City. This 
is called Cassini’s division. Cassini is the man 
who discovered it and saw that it really was an 
empty ring of space. Outside of this dark in¬ 
tervening gap is the outermost ring. It is a 
brilliant white circle that extends in width for 
several thousands of miles, almost equal to half 
the distance around our earth. 

In the meantime, perhaps you have been won¬ 
dering what these Saturnian rings really are, 
what they are made of, and why Saturn is the 
only planet so favored. 

Apparently Saturn’s rings are just as solid as 
the planet itself. But this is only because the 


What are the 
rings made of? 


9 6 


OTHER WORLDS THAN THIS 


How do we \now 
that Saturn is the 
youngest planet? 


earth is so far away that the separate particles 
in the rings seem like one continuous object. If 
you look very closely at an oil painting, you will 
see that it is made up of tiny, separate daubs. 
At a distance these daubs are hard to tell one 
from another. They flow together. The rings, 
then, are made up of individual particles. These 
particles range in size from grains of dust to 
life-sized meteors. Each particle moves around 
the planet with the separateness of a baby moon. 
Occasionally there are collisions, but very rarely. 
When they do collide they fuse together. This 
added weight probably causes them to fall 
closer to the surface of their planet. Thus par¬ 
ticles in the crepe ring are presumably larger 
than the other particles. When the crepe-ring 
particles collide they must fall directly upon 
Saturn. Eventually all the particles may disap¬ 
pear. But it will take millions of years. 

Astronomers believe that all the other planets 
once had rings such as Saturn’s. Rings are, 
therefore, a sign of youth, and Saturn is the 
youngest child of the sun, a planet prodigy. 


OUR BIG BROTHERS 


97 


Saturn’s nine moons are responsible for the 
gap in the rings. They pull the scattered par¬ 
ticles towards them. But they are very small 
bodies and very far away. Their pull cannot 
be very great. Still the chances are that if they 
were any bigger or nearer they would swallow 
up the rings. Perhaps the space where their 
attraction is the strongest is thus swept clear. 

If the particles that compose these rings were 
much farther from Saturn than they are, they 
would combine into another moon. When the 
tiny particles drawn away from a liquid planet 
by the sun do not reach above a certain height, 
the pulling power of their planet is so strong 
that it prevents them from joining forces. Col¬ 
lisions between particles is purely accidental. 
Suppose, on the other hand, that the particles 
could combine into another moon. What would 
happen? The moon would fall straight back 
onto the planet from which it came. The con¬ 
centrated weight of the particles would work to 
their disadvantage. It would increase their 
attractive power. 


Why is there a 
gap in the rings? 


9 8 


OTHER WORLDS THAN THIS 


When was Uranus 
found to be 
a planet? 


It is fortunate for Saturn that he does have 
his beautiful rings. Without them he would be 
a very plain object indeed. He may be the 
second planet in point of size and the first in 
point of lightness, but for all that he is really an 
ugly duckling without his silvery gold halo. 
Seen with the naked eye he gives forth a dull 
yellowish light. Its brilliance, as compared to 
that of the planets nearer the sun, is drab and 
lifeless. 

For thousands of years astronomers looked at 
Uranus with the greatest indifference. “It is 
only one of the fainter stars,” they thought, “not 
worth bothering about.” Then, one beautiful 
night, just about a hundred and fifty years ago, 
something happened that had never happened 
before. The home-made telescope of a certain 
German music-master was trained directly on 
it. Never in all its life had it received so much 
attention. As though to reward the flattering 
gaze of William Herschel, it clearly presented 
the disk-like shape of a planet. But Herschel 
did not jump at conclusions. He patiently 


OUR BIG BROTHERS 


99 


watched the new planet night after night. Not 
until he saw that it really had the same wander¬ 
ing nature as the other planets, did he broadcast 
his discovery. 

Uranus, you may remember, is four times as 
big as the earth, about the size of a medicine ball 
as compared to a six-inch globe. Why then 
does its green-white light shine so palely? In 
the first place, Uranus is so far distant from the 
Sun that it receives only a tiny fraction as much 
sunlight as our earth; in fact, the light of one 
Christmas tree lamp compared with that of 5 
five hundred Watt electric lamps (the amount 
which will flood a tennis court nicely) clearly 
shows the difference in sunlight. In the sec¬ 
ond place, this planet is many times farther 
from the earth than any of the planets we have 
so far examined. 

The distance of Uranus from the heart of the 
solar system is almost two billion miles. Travel¬ 
ing at the deliberate gait of four and one-fourth 
miles a second, it takes eighty-four of our years 
to circle around the sun. Few earth-men live 


Why does Uranus 
shine so faintly? 


Why has Uranus 
such a long year 
and such a 
short day? 


100 


OTHER WORLDS THAN THIS 


Are there people 
on Uranus? 


Can Neptune 
he seen? 


long enough to ring a Uranian New Year both 
in and out. Perhaps to make up for the length 
of this year, Uranus has a very brief day. If we 
could perch on one of its four baby moons, we 
might see Uranus turn on its axis once in about 
every eleven hours. The next time you look 
at one of our sunsets, remember this. Some¬ 
where on Uranus the sun may also be setting, 
but for the second time that day. 

If there are people on Uranus, perhaps they 
eat their luncheon in the dead of night and go to 
bed for a long mid-day nap by candle-light. 
But, of course, there aren’t any people on Ura¬ 
nus. It is probably 340 degrees below zero on 
the surface at noonday. And, like Jupiter and 
Saturn, this planet is almost entirely a gaseous 
body. 

Try, as you may, you will never be able to 
see Neptune unless you look at it through a 
telescope. You can see very plainly, then, that 
it has a disc-like shape and is really a planet. 
The disc is so tiny that little more can be told 
about it. No one knows for certain how 


OUR BIG BROTHERS 


IOI 


quickly Neptune rotates on its axis, though ob¬ 
servers at the Lick Observatory have made an 
estimate of fifteen hours and forty minutes. It 
is, therefore, quite impossible to tell definitely 
how long its day and night are. Again, no one 
knows exactly what sort of an atmosphere it 
has if it shines entirely by reflected light, if it 
keeps the same side always toward the sun, or 
if it has more than one satellite. 

On the other hand, we know certainly that 
Neptune, like Uranus, is about four times the 
size of the earth. This is about the size of all 
the terrestrial planets and their satellites put 
together. We know, too, that it is thirty times 
farther away from the sun than the earth. So 
it received 1/904 as much sunlight. That is 
to say, the earth receives about a thousand times 
as much light as Neptune. But Neptune is 
hardly in total darkness. Sunlight there, at its 
brightest, is somewhere between 520 and 700 
times as bright as our moonlight. All this light 
comes from a sun no larger than the disc of 
Venus, when Venus is nearest the earth. 


What do we 
\now about 
Neptune? 


102 


OTHER WORLDS THAN THIS 


Why does the sun 
rise in the west 
and set in the 
east? 


Do people live 
on Neptune? 


Neptune is indeed a long way from the 
other members of the Solar family. He is so 
far distant that Uranus appears to be the only 
planet between him and the sun. Even Jupiter 
and Saturn are quite invisible, and of course 
Mars, Earth and the other terrestrial planets are 
so near the sun that they are forever hidden by 
its glare. Another curious fact about Neptune 
is its direction of rotation. We do not know 
definitely the length of Neptune’s day, it is true, 
but we are fairly certain that this planet and its 
one moon rotate in an opposite direction from 
the earth, just as Uranus and its satellites do. 
Thus the sun and moon, instead of rising in the 
east and setting in the west, rise in the west and 
set in the east. After her journey through the 
looking glass, Alice in Wonderland would feel 
quite at home in a topsy-turvy world such as 
this. 

It is unfortunate that Neptune is not a fit 
world to live in. If it were not for a number of 
disagreeable features, it would be a fascinating 
place to visit. One of these bad features is the 


OUR BIG BROTHERS 


103 

temperature which is probably 364 degrees be¬ 
low zero at its surface. 

The next drawback is its slight density, one- 
fifth that of the earth. Whether or not it has a 
solid core, it is completely enveloped with a 
cloud-laden atmosphere thousands of miles 
deep. Unless this atmosphere receives heat 
from some other source than the sun, and unless 
it contains breathable substances, it is doubtful 
if any creatures, no matter how unlike ourselves, 
could possibly exist. Neptune’s one point of 
similarity to the earth is its force of gravity. Its 
greater size is offset by its slighter density. 

For twenty-five years astronomers searched 
the skies, night after night, in the hope of discov¬ 
ering the mysterious planet X. In 1905 Dr. 
Percival Lowell noticed that Neptune was 
sometimes pulled outward by an invisible force. 
After making a great many calculations he came 
to the conclusion that a planet beyond Neptune 
was responsible for its irregular orbit. He was 
so certain of the existence of this new planet that 
he devoted much of his time to its discovery. 


Is there another 
planet? 


104 


OTHER WORLDS THAN THIS 


How was it 
discovered? 


He even founded an observatory in Flagstaff, 
Arizona, with this partly in mind. 

Year after year, the astronomers at Lowell 
Observatory struggled with the problem. When 
Dr. Lowell died in 1916, the problem seemed 
no nearer a solution than before. Then in Jan¬ 
uary of 1930, a strange new disc was noticed on 
a photograph of the heavens. At first the 
astronomers thought it might be a comet. But 
after watching it for a while they came to the 
conclusion that it was none other than the new 
planet whose existence Lowell had predicted 
many years before. Whether these astrono¬ 
mers at Lowell Observatory are correct in be¬ 
lieving this object to be the new planet is still 
open to question. No doubt it will be several 
years before definite proof can be shown. But 
in any event due credit should go to the small 
group of men headed by Dr. V. M. Slipher, 
who made the suggestion. 

They have had some interesting things to tell 
about the new planet, if such it is. In the first 
place it is nearly forty-five times as far from the 


What is it li\e? 


OUR BIG BROTHERS 


105 


sun as the earth. The earth receives about two 
thousand times as much light and heat. Sun¬ 
light on Pluto, as it has already been named, is 
pale and ghostly, no brighter than our dim¬ 
mest moonlight. The sun itself is a faint pin¬ 
point of light. 

The planet receives so little heat from the sun 
that the nights can be very little colder than the 
days. The days are about 400 degrees below 
zero. This is only fifty degrees above the 
temperature of space. 

Astronomers at Flagstaff have still to discover 
how fast the supposed new planet travels over 
its orbit around the sun. So no one knows the 
length of its year. It is fairly certain, however, 
that a year on a planet of equal distance from 
the sun is at least three hundred years on our 
own planet. 

It will take many years for the astronomers to 
find answers to all our questions about Pluto. 
Pluto is a difficult subject. He can be seen with 
only the finest and biggest telescopes. Tagging 
bashfully behind his fellow planets he is mak- 


Why do we 
know more 
about it? 


OTHER WORLDS THAN THIS 


Are there 
other planets? 


106 

ing it as hard as possible for us earth dwellers 
to know whether he actually is a planet or any¬ 
thing else about him. 

With Pluto, supposedly the farthest away of 
the Sun’s children, we come to the outermost 
limits of the solar system. Perhaps there is still 
another planet beyond X. Astronomers have 
reason to believe there is. Perhaps you will live 
to see its discovery. In one way or another you 
yourself may contribute to the event. There 
are enough mysteries in the heavens for each 
one of us to have a separate problem to solve, 
if we will. The way to begin is to learn to 
know the heavens; first of all the planets, then 
the stars. 


Chapter VII 


AND THEN WHAT? 

I N the foregoing chapters we have learned 
how the earth came to be, how the solar 
system was created, what the sun is and why it 
remains so hot. We have also become familiar 
with the individual members of the solar sys¬ 
tem, the planets and their satellites. We have 
seen how each is dependent upon the sun for its 
place in the heavens, as well as for its light and 
heat and its habitability. But, you ask, since 
this wonderful orderly universe has had a begin¬ 
ning, will it also have an end? Astronomers 
say the solar order will continue evolving from 
one phase to another, but then what? 

It seems probable that as long as the sun con¬ 
tinues to exist the planets will revolve around it 
just as they are doing today. And as long as it 
continues to shine, they will retain all their 


107 


io8 


OTHER WORLDS THAN THIS 


What will become 
of the earth? 


What will become 
of the sun? 


essential features. Nevertheless, there will be 
some very marked differences. Those terrestrial 
planets that have atmosphere will gradually lose 
it, molecule by molecule. 

Even the earth will lose its beautiful blue 
sky, its seas and its rivers. Eventually it will 
become a dry, barren world with no living thing 
upon it. In the meantime, the major planets, 
with the possible exception of Jupiter and Sat¬ 
urn, may have contracted until they are much 
smaller, and as solid as the earth. In this state 
they may be able to support an atmosphere such 
as we have on our globe today. Under these 
circumstances life may develop. But it in turn 
will die with the certain loss of planetary atmos¬ 
phere. 

The sun will not grow cold for millions of 
years hence. Perhaps it never will. As long 
as the amount of matter it loses through the 
generation of light and heat is constantly re¬ 
newed by stray particles from the surrounding 
space, there is no reason to imagine that it will 
ever die away. Is it not just as reasonable to 


AND THEN WHAT? 


109 

suppose that the sun will plunge into an even 
denser region of nebulous material as to sup¬ 
pose that it will wander into a sparse or arid 
zone? 

Let us see what would happen to our solar 
system in either case. If the sun should travel 
through an unusually rich nebulous region it 
would become bigger and brighter. And the 
planets would become bigger, too. Jupiter and 
Saturn, being the largest of the eight, would 
attract most of the sun’s leavings to themselves. 
The fatter they grew the more they would at¬ 
tract. Eventually they might approach the 
dimensions of a baby star and burst into light 
and heat. In the meantime their distance from 
the sun would have diminished. If, in conse¬ 
quence, they did not swallow up the other 
planets they would certainly push them into 
the sun. Then, if Saturn were thrown in too, 
Jupiter would be the only one left to tell the 
tale. He and the sun would probably form a 
double star. 

Now let us suppose the very opposite. The 


no 


OTHER WORLDS THAN THIS 


What would 
become of the 
solar system ? 


Will new worlds 
be created? 


sun, instead of traveling through the fertile 
fields of space, might be side-tracked in a region 
which is practically empty. It would gradually 
grow smaller. It would begin to condense and 
its light slowly fade, then die out. But all this 
would occupy millions of years. During the 
last million the sunny side of Mercury would 
develop a very agreeable climate. It might 
even be possible for it to retain an atmosphere. 
Life might then commence, only to flourish and 
die just as it had on the other planets. 

When the last spark of life has been extin¬ 
guished on the planets, and the last ray of 
sunlight has died out, the obedient children of 
the Sun will continue to revolve around him. 
Cold and lifeless, invisible as the sun they 
circuit, they will stumble on through darkest 
space, their paths lit only by the pale light of 
distant stars. This would indeed be the end of 
present glories, a ghostly living death. Let us 
hope for an ending more magnificent. 

Today the sun is sweeping through space at 
a rate of eleven miles a second or about four 


AND THEN WHAT? 


hi 


hundred million miles a year. It carries the 
earth and the other planets along with it. As 
far as we can tell it is making straight for the 
beautiful Vega, the fourth brightest star in the 
heavens. But the distance is so great that it 



Eventually the world will die out and become a dry 
barren thing with no life upon it 


will require millions of years for the two to 
come together. In the meantime they may 
both have altered their courses, or on coming 
closer find that they are going to pass each 
other billions of miles apart. 










112 


OTHER WORLDS THAN THIS 


The last time our sun met another star was 
some ten or twenty billion years ago. Astro¬ 
nomers tell us that such an approach occurs once 
in about four millions of billions of years. So 
we may reasonably expect another encounter in 
no less than three quintillion, nine hundred 
quadrillion years from the present. 

Of course our sun may have turned cold long 
before. But for that matter it may have turned 
cold any number of times and each time been 
brought back to light and heat by the simple 
process of wandering into another richly nebu¬ 
lous region. In any event, when it does rub 
elbows with a visiting star, a second solar system 
will probably be born. Then those members 
of our present system which still exist will divide 
and recombine with one another, to become a 
family of new planets. The new planets will 
revolve around a new sun in a different part 
of the heavens. A new order of progress will 
be evolved. Life will then commence, to die 
and recommence somewhere else. Thus will 
our well-loved solar system be perpetuated. 







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